Chapter 8: Photosynthesis Flashcards
(121 cards)
1
Q
photosynthesis
A
the conversion of light energy into chemical energy stored in glucose. occurs in plants, algae, and some bacteria
2
Q
photoautotrophs
A
organisms that use light to synthesize organic molecules (glucose)
3
Q
chemoautotrophs
A
organisms that oxidize inorganic substances like H2S and NH3 to produce energy in the form of glucose
4
Q
photosynthesis takes place in the ______ which is found in _____
A
- chloroplast
- leaves
5
Q
bundle sheath cells
A
type of photosynthetic cells arranged into tightly packed sheaths around the vein of the leaf
6
Q
______ are the major sites of photosynthesis
A
leaves
7
Q
chlorophyll is found in the _______
A
thylakoid membrane
8
Q
chloroplasts are found mostly in the _____
A
palisade mesophyll layer
9
Q
_____ enters the leaf and ______ exits through tiny pores called ______
A
- CO2
- O2
- stomata
10
Q
_____ transports absorbed water to leaves and other parts of the plant
A
xylem
11
Q
______ transports synthesized sugar from leaves to roots and nonphotosynthetic parts
A
ploem
12
Q
sugar is transported in the form of ______
A
sucrose
13
Q
cuticle
A
a thin waxy covering on the outer surface of the leaf
14
Q
the primary function of the cuticle is to _______
A
prevent water loss within the leaf
15
Q
epidermis
A
a layer of cells directly underneath the cuticle
16
Q
xylem
A
upper layer of the bundle sheath cells that transports water
17
Q
phloem
A
upper layer of the bundle sheath cells that transports glucose
18
Q
mesophyll
A
layer of cells within the leaf which can be divided into two layers
19
Q
palisade layer
A
column-like cells in the mesophyll that lie just under the epidermis
20
Q
spongy layer
A
loosely packed cells in the mesophyll that lie between the palisade layer and the lower epidermis
21
Q
the air spaces between the spongy cells allow for _________
A
gas exchange
22
Q
mesophyll cells are packed with _______
A
chloroplasts
23
Q
stomata
A
tiny holes in the leaf within the epidermis
24
Q
guard cells
A
specialized cells that surround the stomata and are shaped like two cupped hands
25
___________ causes the stoma to open or close
changes within water pressure
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if the guard cells are full of water, they _________
swell up and bend away from each other, which opens the stoma
27
if the guard cells have no water, _______
the guard cells close
28
photosynthesis takes place in two stages, __________ and __________
light reaction and dark reaction (calvin cycle)
29
light reaction takes place in the _________
thylakoid membrane
30
the purpose of the light reaction is to ______
use sunlight to produce ATP and NADPH, which are used in the Calvin Cycle to produce sugar
31
the dark reaction (calvin cycle) takes place in the ________
stroma
32
the dark reaction (calvin cycle) uses _________ to make sugar
CO2, ATP, and NADPH
33
light is a form of energy known as ________
electromagnetic energy
34
electromagnetic spectrum is ________
the entire range of radiation
35
all radiation travels as _______
waves
36
wave length
the distance from one wave peak to the next wave peak
37
visible light spectrum
the portion of the electromagnetic spectrum from 380 nm to 760 nm
38
the visible light spectrum is the radiation that __________
drives photosynthesis because it can be absorbed by pigments
39
each pigment has a ________
characteristic absorption spectrum, which is the wavelength of light that is best absorbed
40
light also behaves as particles called ______
photons
41
the energy of photon is __________
inversely proportional to its wavelength
42
pigments are ______
molecules that are good absorbers of light in the visible range
43
two types of pigments used in green plant photosynthesis are _________
chlorophyll and carotenoids
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chlorophyll is made up of ______
a porphyrin head with magnesium in the center and a hydrocarbon tail
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chlorophyll a & b absorb _______
violet, blue, and red light
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chlorophyll a & b reflect _______
green light, which is why plants are green
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_______ are accessory pigments
carotenoids
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carotenoids
capture energy from the light of wavelengths that are not efficiently absorbed by either chlorophyll
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carotenoids absorb _______
blue and green light
50
carotenoids reflect _______
orange and yellow light
51
another accessory pigment is _____
phycobiliproteins, found in cyanobacteria and some algae
52
photosystem organization
the light harvesting unit in photosynthesis located on the thylakoid membrane of the chloroplast
53
the 3 parts of photosystem organization are:
1. antenna complex
2. reaction center chlorophyll a
3. primary electron acceptor
54
the antenna complex consists of ______
chlorophyll, accessory pigments, proteins, and other small molecules
55
the two types of photosystems are:
1. photosystem l
2. photosystem ll
56
photosystem l is composed of _______
chlorophyll a at the reaction center, which is called p700, meaning the wavelength of light that is best absorbed by this chlorophyll is 700nm
57
photosystem ll is composed of:
chlorophyll a at the reaction center, called p680, meaning the wavelength of light that is best absorbed by this chlorophyll is 680 nm
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step 1 of light reaction
light is absorbed by pigments in photosystem ll until it reaches reaction center chlorophyll a. this excites 2 electrons to a higher level in the reaction center chlorophyll p680, where they are captured by the primary electron acceptor
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step 2 of light reaction
an enzyme splits water to extract its electrons to supply it to p680, replacing the lost electrons when light energy was absorbed
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step 3 of light reaction
excited electrons pass from the primary electron acceptor of photosystem ll to photosystem l through the electron transport chain
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step 4 of light reaction
the energy released by the fall of electrons down the ETC is used to pump protons from the stroma into the interior of the thylakoid. protons diffuse back out to the stroma through ATP synthase, producing ATP (chemiosmosis)
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step 5 of light reaction
when an electron reaches the bottom of the ETC, it fills an electron hole in p700. this hole is created when light energy drives 2 electrons from p700 to the primary electron acceptor of photosystem l
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step 6 of light reaction
the primary electron acceptor of photosystem l passes the excited electrons to a second ETC, where NADP+ reductase produces NADPH
64
cyclic-photophosphorylation happens when ________
the cell needs extra ATP
65
dark reaction (calvin cycle) is also known as ________ and _________
carbon fixation & C3 pathway
66
carbon fixation/c3 pathway
incorporates CO2 into organic compound in the form of glucose. the first sugar produced in this cycle is PGA, which contains carbon
67
C3 plants are _______
plants that fix carbon using calvin cycle. ex: rice, wheat, and soybeans
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to produce 1 molecule of glucose _______
2 molecules of G3P, 6 molecules of CO2, and 6 rounds of the calvin cycle are needed
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the 3 stages of the calvin cycle:
1. carbon fixation
2. reduction
3. regeneration
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1st step of calvin cycle
6 molecules of CO2 combine with 6 molecules of RuBP, forming PGA
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2nd step of calvin cycle
PGA is phosphorylated by 12 molecules of ATP, forming 12 molecules of 3C
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3rd step of calvin cycle
3C is reduced by NADPH and undergoes dephosphorylation, forming 12 molecules of G3P
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4th step of calvin cycle
2 of the G3P molecules leave the chloroplast and undergo reversal reactions in the cytoplasm to produce glucose
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5th step of calvin cycle
the remaining 10 molecules of G3P are used to regenerate RuBP
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photorespiration
on hot, dry days, plants **close their stomata** to conserve water. once the stomata closes, photosynthesis **rapidly uses up the CO2** remaining in the leaf and produces O2, which accumulates in the chloroplast. rubisco can react with O2 which competes with CO2 for its active site. rubisco will catalyze the reaction of RuBP with O2 instead of with CO2, making some of the **intermediates** involved in the calvin cycle degrade into CO2 and H2O
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photorespiration occurs in the presence of _______
light
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photorespiration requires ______
O2
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photorespiration produces ____________
CO2 and H2O, but does not yield ATP
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2 photosynthetic adaptations that minimize photorespiration are:
1. C4 photosynthesis (tropical)
2. CAM plants (desert)
80
examples of C4 plants are _________
sugar cane, corn, some grasses
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two distinct types of photosynthetic cells in C4 plants are:
1. bundle sheath cells
2. mesophyll cells
82
process of photosynthesis in C4 plants
CO2 is added to PEP through the stomata to form oxaloacetate through PEP carboxylase. oxaloacetate is reduced by NADPH to malate. mesophyll cells export malate to bundle sheath cells through plasmodesmata. malate releases CO2 in the bundle sheath cells which enters the calvin cycle. this keeps the concentration of CO2 high enough for rubisco
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step 1 of photosynthesis in CAM plants
the plant will open the stomata during the night and close it during the day
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step 2 of photosynthesis in CAM plants
during the night, the plant takes CO2 and incorporates it into organic acids like malate using C4 pathway
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step 3 of photosynthesis in CAM plants
the mesophyll cells of CAM plants store malate in their vacuoles until daytime where the stomata closes
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step 4 of photosynthesis in CAM plants
during daytime, CO2 will be released from malate and will be used in calvin cycle to produce sugar
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photosynthesis is different in cyanobacteria because ________
there is no chloroplast, so light reaction will take place in the plasma membrane where pigments exist. dark reaction takes place in the cytoplasm
88
equation for photosynthesis
6CO2 + 12H2O ———> C6H12O6 + 6H2O + 6O2
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the role of chlorophyll is to _______
absorb light
90
equation for photosynthesis in sulfur bacteria
CO2 + 2H2S ———> CH2O + H2O + 2S^
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in sulfur bacteria, only _______ photosystem is used
one
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sulfur bacteria uses an electron donor such as _____ rather than water, so _______ is not released
H2S & O2
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electrons from H2S are used to _______
reduce NADP+
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in sulfur bacteria, the calvin cycle happens in the ________
cytoplasm
95
light affects rate of photosynthesis because _______
increasing light intensity will increase the rate of photosynthesis until the light reactions are saturated with light energy
96
CO2 concentration affects rate of photosynthesis because __________
increasing CO2 concentration increases rate of photosynthesis until it reaches the CO2 saturation point, where any more increase has no effect
97
temperature affects rate of photosynthesis because ________
increasing temp will increase rate of photosynthesis until a certain point, 35°C. beyond this point, rate of photosynthesis will decrease because enzymes in the reaction will denature AND stomata will close to limit water loss
98
_________ can be used to measure the absorption spectrum of a substance
spectrophotometer
99
water affects rate of photosynthesis because _________
lack of water will slow rate of photosynthesis stomata will close from water loss
100
the metabolic reaction in photosynthesis is ______
anabolic
101
the raw material in photosynthesis is _______
CO2, H2O, & O2
102
ATP production process in photosynthesis is ________
ETC
103
the location of the ETC is _______
thylakoid membrane
104
electron acceptor in photosynthesis is _______
NADP+
105
transpiration is __________
water continuously evaporating from the surface of leaf cells exposed to air
106
plants transpire for _________
evaporative cooling
107
evaporative cooling
as water converts from a liquid to gas at the leaf cell, energy is released. this process uses energy to break the strong H bonds between H2O molecules. the gas molecules will release into the atmosphere, which cools the plant
108
explain how the stomata opens
when stomata is signaled to open, K+ enters the guard cells, creating a hydrostatic pressure that changes the shape of the stomata. the guard cells expand on the outer edges of the stomata, but not on the inner side, resulting in kidney-shaped cells & an opening between 2 guard cells for has exchange
109
explain how the stomata closes
guard cells lose water & become flaccid. K+ moves back out of the guard cells, followed by H2O, which lowers pressure in the guard cell
110
the stomata is signaled to close by:
1. lack of water
2. internal CO2 concentration is high
3. temperature is too higher
111
the equation for how factors affect transpiration is _______
[water potential(leaf)] - [water potential(atmosphere)] / resistance
112
the factors affecting rates of transpiration are:
1. stomata
2. boundary layer
3. cuticle
4. relative humidity
5. temperature
6. soil water
7. light
8. wind
113
stomata affects rate of transpiration because __________
when stomata is **open**, transpiration rates **increase**
114
boundary layer affects rate of transpiration because __________
the **larger** the boundary layer, the **slower** the rates of transpiration
115
cuticle affects rate of transpiration because __________
the **thicker** the cuticle, the **slower** the rate of transpiration
116
relative humidity affects rate of transpiration because __________
the **higher** the relative humidity, the **lower** the rate of transpiration
117
temperature affects rate of transpiration because __________
the **higher** the temperature, the **higher** the rate of transpiration because there is less water in the air, so water can always move from leaf to air
118
soil water affects rate of transpiration because __________
the **more moisture**, the **higher** the rate of transpiration because there is enough water to move through the plant
119
light affects rate of transpiration because __________
in the light, stomata is open, so transpiration rates will **increase**
120
wind affects rate of transpiration because __________
the **windier** it is, the **higher** the rate of transpiration because the leaf’s boundary layer is smaller
121
the boundary layer is _______
a thin layer of still-air hugging the surface of the leaf, which is not moving
